Vehicles which employ an electric motor as a power source, such as hybrid and electric vehicles, are gaining popularity as a substitute for conventional gasoline engine vehicles in light of global environmental issue.
Moreover, energy storage units which include a plurality of energy storage devices such as lithium ion secondary energy storage devices are widely used as energy sources for supplying power to the electric motors in these hybrid vehicles.
With this kind of energy storage unit, a plurality of energy storage devices, which are electrically connected by bus bars provided between neighboring energy storage devices, are arranged in a covering member made of a rigid metal.
Patent Literature 1 (Japanese Unexamined Patent Application Publication No. 2011-216400) discloses a technique to prevent electrical shorting between the bus bar and the metal covering member in this kind of energy storage unit.